2011-2012 Winter: La Nina Officially Declared

http://www.noaanews.noaa.gov/stories2011/20110908_lanina.html

A La Nina has officially been declared, and here's what's going down.

-Coldest temperatures APPEAR to be in western areas.
-CFS model says this La Nina could be stronger.

Here's current SST (Sea Surface Temperatures)

GFDL Hurricane Model has Maria Close in on Florida, Landfall Likely in this scenario

The latest GFDL has Maria travel NW, dance around the islands before likely making landfall on Florida as at least a hurricane. As of right now, it appears Maria may degenerate into a tropical wave but restrengthen, and here's why.
Maria is currently a weak tropical storm. She does not have a defined circulation, which I am anticipating a RECON aircraft will confirm tonight. She has a patch of clouds in her center (figure 1), which you can see is exposed from the main convection to the north of Maria (figure 2) with center roughly drawn in.

Figure 1- red and blue box is storm's center.

Figure 2- red areas indicate heaviest storms

Maria isn't in an environment favorable for development, and several models are not calling for any strengthening. Below, in Figure 3, you see Maria with a superimposed image of current wind shear in knots. Figure 4 is the official NHC track right now.

Figure 3

Figure 4

GFS Rams TS Nate into New Orleans as a hurricane

The GFS's latest run has put New Orleans in an unfavorable position as the model throws Nate towards the city. This is your morning TS Nate Update. Here is a GFS image of forecast surface wind speeds.

Nate is being smashed into the Gulf coast with winds possibly exceeding 40 knots. With a defined eye in this image and all the other images, it would be logical to indicate that Nate will likely become a hurricane in any situation. The only thing to watch is the track. Here's another image from the GFS with MSLP.

This image looks to be more suitable for hurricanes. The GFS shows a portion of Nate in light red, which is shown on the legend as over 64 knots of wind speed. MSLP indicates a low pressure of 992 millibars, which is a fairly good strength for a tropical storm or low end category 1 hurricane.
Here is the NHC's track, then spaghetti models.

The consensus does appear to be towards Mexico, which is where I will point to as well, but I am leaving the door open for a potential threat to Louisiana and/or the entire Gulf Coast.

Tropical Storm Nate Forms in the Bay of Campeche, off shore of Mexico

TS Nate has formed offshore the coast of Mexico in the Bay of Campeche. The NHC has not officially released tracks and wind forecasts for this system, but estimates are that Mexico and possibly the US will be affected. Here is the ECMWF portrayal of Nate.

The ECMWF allows Nate to develop into a hurricane, then make landfall on Mexico, only affecting South Texas with outer wind bands. Only sprinkles may come from that system if this verifies. These forecasts are still considered 'long-range', so they will be changing over the next several days.

Midwest Chill not Over, but Warming Trend to come?

The cold air mass stationed over the Eastern Half of the US will continue to stick around for at least another 5 days, but slow, gradual warming will occur during this period. Here's an 8-day portrayal of forecast temperature anomalies compared to normal temperatures.

Note: Anomalies are in CELSIUS 

Despite this cold air mass, warming is forecast by the GFS ensemble members. Below is an image of 10 days out temperatures.

Ensembles indicate the cold air mass over the US is forecast to dissipate as a warmer air mass moves in from the northwest US and Canada. Below is the Day 15 forecast temperatures by the same GFS ensemble members.

At this point, some GFS ensembles indicate strong warming is to take place in the Central US, but together they indicate the cold air mass fading and a modestly warmer air mass to move across the US.